A cellulose acetate film has high strength and flame retardant properties (‘flame resistance’), thus being used for various photographic or optical materials. Compared with other polymer films, the cellulose acetate film has relatively low optical anisotropy which exhibits low retardation, therefore, is used for a polarizer.
In recent years, a liquid crystal display device having high performance such as improvement in image quality is increasingly required. Accordingly, a cellulose acetate film used for a polarizer, which is a material also used in a liquid crystal display device, also needs characteristics satisfying the foregoing requirements. More particularly, in case of an in plain switching (IPS) mode liquid crystal display device, in order to overcome problems related to variation of colority and enhance a contrast ratio, there is a need to reduce optical anisotropy of the cellulose acetate film (Re—retardation value in the film plane; Rth—retardation value in the film thickness direction). Accordingly, the development of cellulose acetate films capable of the foregoing is now being strongly demanded.